An often used commercial system for the separation of a mixture comprising oxygen, nitrogen and argon, e.g. air, is cryogenic rectification. A valuable product produced by such cryogenic rectification is high purity oxygen. However generally in the production of high purity oxygen by cryogenic rectification, as the oxygen purity increases, the yield or recovery of the oxygen decreases. The recovery of high purity oxygen by means of cryogenic rectification may be improved by adding additional stages to the cryogenic rectification column system. However, this procedure increases both the capital and the operating costs of the cryogenic rectification system, especially if trayed column sections are used.
Accordingly it is an object if this invention to provide an improved cryogenic rectification method for producing high purity oxygen with improved recovery.
It is another object of this invention to provide an improved cryogenic rectification apparatus by which high purity oxygen may be recovered with improved recovery.